This invention relates to a novel mineral stabilized resin emulsion which can be utilized as a decorative and/or protective surface coating. Further, the present invention provides a method for producing the emulsion by effecting a dispersion of an acid modified hydrocarbon resin in an aqueous medium and stabilizing the dispersion by the addition of a complexing agent compatible with the acid modified resin, and a mineral stabilizer such as bentonite clay.
Low to zero acid number hydrocarbon resins which heretofore have not been emulsified in the mineral colloid system are rendered capable of being emulsified in the present system by the addition of organic acid(s) soluble in them, and whose reaction products, with the aqueous complexing agent, has at least a slight solubility in water. Additionally these resins may advantageously be filled and/or pigmented prior to emulsification by any system.
Some prior emulsification processes have utilized colloidal clay-like materials for the emulsification and stabilization of asphalt emulsions. Although prior asphalt emulsions weather satisfactorily when applied to a base sheet, they are difficult to pigment and thus asphalt emulsions have generally been used in conjunction with an overlying decorative layer such as an acrylic coating. However, the use of acrylic coatings to cover asphalt emulsions has not met with complete success due to various differences in their individual properties, for example, differences in water absorption, toughness, softening points and variations in the co-efficients of thermal expansion. While acrylic coatings will suitably perform as a decorative/weather coating when used alone, the acrylic coatings are quite expensive and decompose at relatively low temperatures due to their relatively low flash points.
Moreover, these prior asphalt emulsions do not always attain an equilibrium condition within a relatively short time and as a result these emulsions may frequently undergo changes on aging. In this regard, many factors contribute to the stability of an emulsion including particle size, density of phase components and conditions of storage, such as temperature, agitation or evaporation during storage and use.
The drawbacks associated with prior asphalt emulsion and acrylic coating materials have led to the development of the present novel mineral stabilized resin emulsion which is similar to the prior asphalt emulsions in appearance but can be easily pigmented and used either by itself as a decorative weather coating, as an outer protective coating applied to an underlying asphalt emulsion, or applied as a coating to roofing paper and optionally surmounted with a granular material or other suitable surfacing agent. Further, the present mineral stabilized resin emulsion produces a dry emulsified film which is water resistant and more resistant to flow at elevated temperature.